Signs for advertising the location of public telephones generally are constructed in a square or rectangular configuration with wording and/or graphics denoting the location of a telephone being visible from front and back faces. The most widely used of such signs has an extruded aluminum frame structure extending around its periphery and defining the thickness of the sign. Grooves are provided inside the frame for supporting front and back plastic faces which are slid into position when one side of the frame is swung up to the disengaged position by being pivoted around a hinge provided for that purpose. Upon insertion of the sign faces, the hinge frame side is rotated downward and secured in engaged position by being connected to an adjacent side of the frame. Internal components of the sign, including fluorescent light fixtures, ballasts, and necessary wiring, are supported along one side of the frame and on brackets that extend across the sign, the bracket being connected at their ends to other, opposing sides of the frame. This type of sign is exemplified by the PB-23 Lighted Sign available from Phillips & Brooks, Inc., Cumming, Ga.
A sign structure having a perimeter frame of extruded material for supporting front and back sign faces is also disclosed in U.S. Pat. No. 4,205,471, issued June 3, 1980, to Coleman, and in U.S. Pat. No. 4,317,302, issued Mar. 2, 1982, to Sernovitz. All of these signs include peripheral metal frames for securing sign faces and internal clamps or brackets connected to opposing sides of the frame. These features tend to interfere with access to the sign interior and to complicate installation and maintenance procedures. In addition, the presence of a peripheral metal frame keeps the frame sides from being illuminated internally so that the sides would not be suitable for graphic displays. It is desired to provide an illuminated sign of simpler construction that avoids the need for a peripheral frame support and that has frame sides as well as faces available for graphic display.